1. Field of the Invention
The present invention relates to a multilayer film for plating, a method of manufacturing a metal film-coated material and a metal film-coated material, and more specifically, a multilayer film for plating capable of forming a plating receptive layer on any substrate surface, a method of manufacturing a metal film-coated material using the multilayer film, and the metal film-coated material obtained using the manufacturing method.
2. Related Art
In recent years, with demand for highly-functional electric devices and the like, the high-density integration of electronic components, the high-density packaging and the like have been advanced, and to this end, miniaturization and high-density technology of printed circuit boards applicable to these the high-density packaging and like have also been advanced.
The copper clad laminates (CCL) in which a metal film is formed on the surface of an insulating resin film or various insulating laminate material have been widely used in order to produce boards for packaging semiconductors for driving for displaying an image on a liquid crystal display, or boards used for a movable part which requires flexibility. In recent years, a COF [chip-on film] has received attention as a technique of packaging a driver IC chip for displaying a liquid crystal image display. It is said that the COF enables fine pitch packaging and miniaturization of a driver IC and costs reduction, as compared with the TCP (tape carrier package) which is the mainstream in the conventional packaging method. In recent years, in the COF, electronic circuits with high definition and fine pitch are strongly required with the recent development of a liquid crystal display screen with high definition and the miniaturization of an IC for driving liquid crystal.
In forming these fine pitch wirings, the “subtractive method” and the “semi-additive method” as methods of forming conventional conductive patterns, in particular, methods for forming metal patterns useful in the field of the printed circuit boards have been known.
The subtractive method is the method in which a photosensitive layer sensitive to irradiation with actinic light on a metal film formed on an insulating resin film of a copper clad laminate is provided, and the photosensitive layer is imagewise exposed, and subjected to development to form a resist image, subsequently, a metal pattern is formed by etching, and finally, the resist is peeled off. The copper clad laminate used for the subtractive method is prepared in such a manner that a resin varnish layer is formed on a metal foil and is cured; a thermoplastic layer is formed on an insulating resin film, and a metal foil is laminated on the thermoplastic layer; or an electric power supply layer formed by a certain method is formed on the surface of an insulating resin film and an electroplating of the electric power supply layer is performed by flowing electric current. As the electric power supply layer formed by this technique, a plating method, a sputtering method, a vapor-deposition method, or a thin metal foil laminating method is used.
On the other hand, the semi-additive method is the method in which an electric power supply layer formed by a certain method is formed on the surface of an insulating resin film, and a photosensitive layer sensitive to irradiation with actinic light is formed on the electric power supply layer, and the photosensitive layer is imagewise exposed, and is subjected to development to form a resist image, and an electroplating of the electric power supply layer is performed by flowing electric current. After a metal wiring is formed in the area where the resist is not formed, the electric power supply layer where the metal wiring is not provided is subjected to an etching process to form a metal pattern. As the electric power supply layer formed by this technique, a plating method, a sputtering method, a vapor-deposition method, or a thin metal foil laminating method is used. In this method, a copper clad laminate, in which a metal film is formed, is also preferably used.
As the copper clad laminate used for the above subtractive method and the semi-additive method, it has been known that a laminate for a flexible printed circuit board, in which a polyimide film is subjected to a plasma treatment, followed by a silane coupling treatment, and after a catalyst is adsorbed thereto, an electroless plating and electroplating plating are performed, is prepared (for example, Japanese Patent Application Laid-Open (JP-A No. 2005-54357). The laminate does not require a special adhesive layer, and does not particularly require the surface-roughening treatment of the polyimide film by virtue of the plasma treatment and silane coupling processing, and has the metal film excellent in adhesiveness with the polyimide film, but a large-sized apparatus for the plasma treatment and the like is required.
As a method of forming a metal pattern excellent in the insulation reliability among wirings, a method of hydrophobicizing with a plating pretreatment after a plating receptive layer is formed using a graft polymer is disclosed (for example, refer to JP-A No. 2006-237400). However, in this method, since a primer layer or a graft layer is formed by a coating method, a pattern coating such as an inkjet method or a printing method is required when it is desired to form a pattern in part, is required, and a high definition pattern formation is difficult. On the other hand, the method in which a plating receptive layer formed by a transfer method is used for a primer layer, is also disclosed (for example, refer to JP-A No. 2007-125862). However, in order to form a layer on a hydrophobic surface with the use of a transfer method, it is necessarily required that both a primer layer and an adhesion auxiliary layer (graft layer) are laminated, and, there is a fear that an additional process, in which the primer layer is transferred to the hydrophobic layer in an extra process, is required. Further, the plating receptive graft layer used here is composed of a hydrophilic polymer, the adhesiveness between the primer layer and the adhesive auxiliary layer prior to the transfer is poor, and there are problems such that the primer layer tends to be insufficiently transferred.
Moreover, a method of forming a pattern and forming a metal film using a transfer film has been known for many years, and, for example, the method in which a metal film formed by a vapor deposition process and the like are transferred to the surface of a board is generally used (for example, refer to JP-A No. 2004-243752), and in the transfer of the metal film, unevenness caused by the transfer tends to arise and the method is not suitable for a high definition wiring.